You can still sponsor your husband even if you currently live in Australia. My husband lives with me in Sweden and was approved as a sponsor very quickly. The only thing is you need to include "proof" of that you will move back to Canada once your husbands PR is approved. It could be a lease, job offer, morgage....etc. We didn't have any of that since it's difficult go get from oversease but we included lots of other things as proof of both of us setteling in Canada once my PR was approved, we sent letters from friends and family with offers of us staying with them until we get our own place, emails between us and colleges we are applying for, facebook statuses...yeah anything really that can confirm your intentions of moving back
This was actually the part I was mostly nervouse about while waiting for our application to finish. If you have more questions don't hesitate to ask!
Good Luck!